Diabetes mellitus is a groups of diseases associated with regulation of sugar blood (typically glucose concentration) levels. Various pharmacological and non-pharmacological treatments are known, however periodic monitoring of blood sugar levels provides effective, long-term, supporting treatment and may enable relatively normal day-to-day life.
Various techniques are known for monitoring glucose blood levels, most of these techniques require invasive measurements, e.g. by drawing a drop of blood for direct measurement of glucose levels. Lately, various non-invasive techniques have been devised in the field of measuring blood-related parameters, such as glucose level and others. The existing non-invasive techniques include impedance-based techniques as well as optical measurement techniques. For example, in glucose meters based on near infrared spectroscopy, a tissue is illuminated with light in the infrared spectrum, and one or both light reflected by the tissue and light transmitted through the tissue are measured. The portion of light that is reflected and/or transmitted is indicative of the blood glucose level. Such glucose meters are used for tissue investigation in different depths varying from 1 to 100 millimeters or 10 to 50 micrometers.
Some glucose meters use Raman spectroscopy to measure scattered light that has been influenced by the oscillation and rotation caused by glucose. Glucose meters based on photo-acoustic spectroscopy measure parameters of an acoustic pressure wave created by rapid heating of the sampled area. Other glucose meters measure changes in the scattering and the polarization parameters of light caused by glucose. Femtosecond pulse interferometry can be used to determine glucose concentration, by measuring the group refraction index of a glucose solution using a time delay of femtosecond order in a time-of-flight method. Optical coherence tomography can be used to measure and analyze the interference pattern between the coherently backscattered light from specific layers of tissues and a reference beam.
Optical techniques for monitoring and measuring various parameters of a sample, including blood related parameters have been described. Such techniques include:
US2014148658 presents a system and method for use in monitoring one or more conditions of a subject's body. The system comprises a control unit which comprises an input port for receiving image data and data indicative of at least one external stimulation (external field) applied to a portion of the subject's body during collection of the image data therefrom, a memory utility, and a processor utility. The image data is indicative of a sequence of speckle patterns generated by the portion of the subject's body according to a certain sampling time pattern. The processor utility is configured and operable for carrying out the following: processing the image data utilizing the data indicative of the applied external field(s), said processing comprising determining a spatial correlation function between successive speckle patterns in the sequence, and determining a time varying spatial correlation function in the form of a time-varying function of at least one feature of the correlation function indicative of a change of the speckle pattern over time; selecting at least one parameter of the time-varying spatial correlation function, and applying to said at least one parameter one or more of the models to determine one or more corresponding body conditions; and generating output data indicative of said one or more corresponding body conditions.
U.S. Pat. No. 8,638,991 presents a method for imaging an object. The method comprises imaging a coherent speckle pattern propagating from an object, using an imaging system being focused on a plane displaced from the object.
General Description
As indicated above, optical monitoring may provide non-invasive and efficient techniques for determining and observing parameters of a patient. Further, the use of coherent illumination and detection of variation in secondary speckle patterns generated in light returning from an inspection region of the patient (herein referred to as speckle-based detection) can be used for measurement of various biophysical parameters and provide robust and simple monitoring technique.
The present invention utilizes such speckle-based optical monitoring for simplifying routine monitoring of glucose levels in user's blood, enabling effectively continuous monitoring of glucose levels while limiting the need for invasive blood sampling. To the end the technique of the present invention utilizes detection of correlations between image data pieces associated with speckle patterns in light returning from an inspection region on the user's body, for continuously determining data about heart rate of the user; and utilizing the heart rate data in accordance with pre-provided calibration data connecting heart rate variability with varying levels of glucose in the user's blood.
The technique of the present invention, is based on speckle-based monitoring, where correlation functions between speckle patterns collected in different (consecutive) image data pieces are used for obtaining data about physical/mechanical movement of the inspection region. More specifically, variation in location or orientation of at least a part of the inspection region affect arrangement of the so-collected speckle patterns and can thus be detected based on correlation between speckle patterns. The technique of the invention utilizes detection of vibrations associated with blood pulsating due to heart beats and resulting in periodic vibration pulses that may be detected from effectively any selected location (inspection region) on the body. Based on the heart rate data detected using the speckle-based monitoring, the present technique utilizes determining at least one variability parameter indicative of variations in the heart rate of the user, for determining data on variations in glucose concentration of the user.
The present invention generally provides a system for monitoring glucose levels, according to some embodiments of the invention the system comprising a light source unit configured for providing coherent optical radiation and directing it onto a selected inspection region on a user's body (e.g. hand, arm etc.), a collection unit configured for collecting light returning by reflection and/or scattering from the inspection region and generate a plurality of image data pieces associated with secondary speckle patterns formed by light interference, and a control unit. The collection unit comprises an imaging lens arrangement and a detector array located at a selected distance from the imaging lens arrangement such that and image formed on the detector array by the imaging lens arrangement corresponds with an intermediate plane located in optical path of light propagation from the inspection region toward the collection unit.
The control unit is configured and operable for receiving input data comprising a plurality of image data pieces, each indicative of a detected speckle pattern, and processing the input data in accordance with pre-stored calibration data for determining data on glucose levels in user's blood. The control unit typically comprises a processing utility, storage utility (e.g. memory unit) and input port for receiving data from the collection unit and output port (e.g. network communication and/or user interface). The processing utility comprises hardware/software modules such as correlation module configured for determining correlation between consecutive speckle patterns in image data pieces, heart rate module configured for processing data on the correlation functions and determine accordingly data on heart rate of the user, HRV module configured for determining heart rate variability measure based on heart rate data, and glucose module configured for utilizing heart rate variability measure and pre-stored calibration data, stored at the storage utility, for determining data on glucose concentration in user's blood. The control unit may then generate user indication data indicative of glucose levels and provide it to the user or selected physician. Additionally, the data on glucose levels may be stored for monitoring and additional processing.
Thus, according to a broad aspect, the present invention provides a system for monitoring glucose blood level of a user, the system comprising an illumination unit configured for providing coherent optical illumination on a selected inspection region on the user body, a collection unit configured for collecting light returning from the inspection region and generating a plurality of image data pieces associated with speckle patterns in the collected light, and a control unit comprising a processing utility and storage utility comprising pre-stored calibration data, the processing utility is configured for receiving input data on a plurality of image data pieces from the collection unit and for processing said input data for determining correlation functions between different image data pieces and using said correlation functions and said pre-stored calibration data for determining data on glucose blood level of the user.
According to some embodiments, the processing utility may comprise one or more processors comprising: correlation module configured for receiving plurality of image data pieces and for determining correlations between consecutive image data pieces and generating at least one time correlation function associated with variation between speckle patterns in said plurality of image data pieces; heart rate module configured for receiving data on said at least one time correlation function and applying one or more selected filters for determining heart rate data of the user from said at least one time correlation function; heart rate variability (HRV) module configured for receiving said heart rate data over selected measurement time and determining at least one variability parameter indicative of variation in heart rate of the user within the measurement time; and glucose module configured for receiving said at least one variability parameter and determining data on glucose concentration in blood of the user in accordance with pre-stored calibration data and said at least one variability parameter.
According to one other broad aspect, the present invention provides a system for monitoring glucose blood level of a user, comprising a processing utility, storage utility comprising pre-stored calibration data and input port configured for receiving input data in the form of a plurality of image data pieces associated with speckle patterns collected from a selected inspection region; the processing utility comprising: correlation module configured for receiving said plurality of image data pieces and determining correlation functions between consecutive speckle patterns, heart rate module configured receiving and processing said correlation functions and determining heart rate data therefrom, HRV module configured for receiving heart rate data from the heart rate module and processing the heart rate data for determining heart rate variability measure, and a glucose module configured for processing said heart rate variability measure in accordance with calibration data stored in the storage utility and determining data about glucose blood level of the user.
According to yet another broad aspect, the present invention provides a software product embedded on a non-transitory computer readable medium and comprising computer readable instructions that when executed by one or more processors causing the processor to:
being responsive to obtain one or more sequences of image data piece, each comprising at least one pattern of secondary speckles collected from an inspection region on a user;
processing the one or more sequences of image data piece for determining at least one time correlation function indicative of variations between speckle patterns in the sequence of image data pieces;
filtering said at least one time correlation function for determining variations associated with heart rate activity and determining heart rate variability measure being indicative of frequency variations of said heart rate activity within selected monitoring period;
obtaining, from a storage utility, calibration data indicative of glucose levels of the user and determining current glucose level in accordance with said heart rate variability measure; and
generating indication on current glucose measure.
According to yet further broad aspect, the present invention provides a method for use in determining glucose levels of a subject, the method comprising: providing one or more sequences of image data piece, each comprising at least one pattern of secondary speckles collected from an inspection region on a user; processing, by a computer processor, the one or more sequences of image data piece for determining at least one time correlation function indicative of variations between speckle patterns in the sequence of image data pieces; filtering said at least one time correlation function for determining variations associated with heart rate activity and determining heart rate variability measure being indicative of frequency variations of said heart rate activity within selected monitoring period; obtaining, from a storage utility, calibration data indicative of glucose levels of the user and determining current glucose level in accordance with said heart rate variability measure; and generating indication on current glucose measure.